2.5 and 8.1

Competitive Inhibitors

-Interfere with the active site so that the substrate cannot bind. -Reduces the overall rate of reaction.

Lactose-Free Milk

-Lactose is the sugar that is naturally present in milk. -Glucose + galactose --> lactose -Lactase is obtained from Kluveromyces lactis, a type of yeast that grows naturally in milk. -Biotechnology companies culture the yeast, extract the lactase from the yeast and purify it for sale to food manufacturing companies. Reasons: -Lactose-intolerant people -Galactose and glucose are sweeter than lactose, so less sugar needs to be added to sweet foods containing milk. -Glucose and galactose are more soluble than lactose. -Faster production because bacteria ferment glucose and galactose.

Enzyme Immobilization Advantages

-The enzyme can easily be separated from the products of the reaction, stopping the reaction at the ideal time and preventing contamination of the products. -After being retrieved from the reaction mixture the enzyme may be recycled, giving useful cost savings, especially as many enzymes are very expensive. -Immobilization increases the stability of enzymes to changes in temperature and pH, reducing the rate at which they are degraded and have to be replaced. -Substrates can be exposed to higher enzyme concentrations than with dissolved enzymes, speeding up reaction rates.

Three Stages of Enzyme Activity

-The substrate binds to the active site of the enzyme. Some enzymes have two substrates that bind to different parts of the active site. -While the substrates are bound to the active site they change into different chemical substances, which are the products of the reaction. -The products separate from the active site, leaving it vacant for substrates to bind again.

Ways in which enzyme activity is affected by temperature.

-When liquids are heated, particles move more rapidly, increasing the chance of a collision between enzymes and substrates. -When enzymes are heated, bonds in the enzyme vibrate more and the chance of the bonds breaking is increased. This causes the structure of the enzyme to change, called denaturation meaning it is no longer able to catalyze reactions.

Ways in which enzyme activity is affected by pH.

-pH is used to measure acidity or alkalinity. -The lower the pH, the more acidic. The higher, the more alkalinity. -Change in pH affects the shape of the enzyme. Another example of denaturation.

Denaturation

A loss of normal shape of a protein due to heat or other factor. In many cases, this causes enzymes that were dissolved in water to become insoluble and form a precipitate.

Metabolism

All of the chemical reactions that occur within an organism. -Most chemical reactions take place in a series of small steps, forming what is called a metabolic pathway. -Most metabolic pathways involve a chain of reactions. -Some metabolic pathways form a cycle. This means that the end product is what started the cycle.

The Buchners Brothers Discovery

An extract of yeast, containing no yeast cells, would convert sucrose into alcohol. This created the opportunity for the use of enzymes to catalyze chemical processes outside living cells.

Non-Competitive Inhibitors

Bind at a location other than the active site.

Enzymes and Activation Energy

Enzymes lower the activation energy.

Rate of Activity of Enzymes

Factors: Temperature, pH, and substrate concentration.

Enzymes

Globular proteins that work as catalysts. Also known as biological catalysts because they are made by living cells and speed up biochemical reactions.

Ways in which enzyme activity is affected by substrate concentration.

Increased chances of substrates and enzymes colliding. However, more enzymes are filled up and so the rate at which enzymes catalyze reactions get smaller and smaller as substrate concentration rises.

Substrates to Products

Substrates have to pass through a transition first, which requires energy. However, at certain times, energy is also released. The energy that must be put in is called activation energy, which is used to break or weaken the bonds. The binding of the substrate to the active site, as a result, lowers activation energy. *See 8.1, Figure 4

Enzyme-Substrate Specificity

The ability of an enzyme to choose exact substrate from a group of similar chemical molecules. Enzymes of a certain type can only collide with only a certain type of substrate.

Immobilized Enzymes

The attachment of the enzymes to another material or into aggregations, so that movement of the enzyme is restricted.

Collision

The coming together of a substrate molecule and an active site. This occurs because of the random movements between substrates and enzymes.

Allosteric Interactions

The modification of an enzyme's configuration through the binding of an activator or inhibitor at a specific binding site on the enzyme. This effectively powers on/off the enzyme as needed. The product made by a substrate binding to an active site can enter the allosteric site and inhibit the enzyme. This is known as controlling the metabolic pathway. For example: The conversion of threonine to isoleucine.

Active Site

The part of an enzyme where the chemical reaction occurs by the binding of the substrate. Shape and chemical properties of the active site and substrate match each other.

Substrates

The reactants that bind to the enzyme and the enzyme converts into a product.

Reaction Results

The substrates are dissolved in water around the enzyme after the reaction.